Pivotally mounted return connection



United States atentA PIvorALL-Y MOUNTED RETURN CONNECTION.

Frank J. Rickert, Philadelphia, Pa., assigner to I-T-E Circuit BreakerCompany, Philadelphia, Pa.

Application August 14, 1953, Serial No. 374,400

8 Claims. (Cl. 200-144) invention relates to circuit.' breakers andis,more particlarlydirected to a pivotally mounted returnconnection-which--is in electrical engagement with a movablecorntactharmgonly during the initial openingfmovement, thereof.. l.,"Inf'the prior art arrangements, circuit breakers have been designedwith both astationary front arcin'gk horn.. anda/permanent flexible leadconnectionfrom the front ofJ the arc chute to the movable contact.Thus,` duringV thegopening operation of the circuit breaker, the above:configuration formed by the front and back archorn provide-'a-venturieiect for the arc to thereby force it into. thefarc chute. This venturielect, due to the position of" thearehorns, exists only duringtheinitial opening. movementeof the movable contact. Thus, after 'the arcis forced intojthe yarc extinguishing umeansiand the mov,- alblecontactarm has moved to its completelyropeny positibn'it is' necessary toprovide the above mentioned re-` tiirn'pathfromthe front end of the archornto the, movablle'A contactarm. This' arrangement was. necessary l inorderto Vavoid the highly undesirable. striking of an ,arc betweenthefron't end ofthe arcA chuteand the movable. eontactlarnr toitherebyioniZe the gases :in this region; Thus, 'itfwas necessary to provide apermanent ilexible. connection from the front end of the arcchute to.the rhovable i contact arm in orderl to eliminate. restriking andihizationof the gases in the region surrounding the movblejpcontacts. It' t lthughi the permanent return connection from the aifc bhutet'oithemovable contact arm has the advantage of eili'tniiiat'ii'i'g'"the4'above mentioned undesirable eiect, n inherent disadvantage when thecircuit breaker he completely open static condition.

jthough` the "arc plates of the arc chute are ymade n 'rsiilatiriglmaterial, a moist atmosphere may resultin a conductiiigr'p'ath from thestatinarydcontact thloilh thefarcplatesof'the arc'chute down throughythe ilexible'fretiirn lead to the movable contact arm.y Thatisyfv'erittiougli the vcircuit breaker is `in-the fully open-posi' titi theYsourcepotential applied across the disengaged bopeating contactsyrnaylind an electrical pathtlirough thefarc -chute 'f'fth'erebyresulting` in currentaowxgeven though'the circuitbreaker isin thefullyopen'position;

VAlthough the magnitude of the current ,owing through th'e"arc" chutewhen the circuity breaker Iisin thestatic open .position may only beofthe magnitude-.cfa few milli amperesf, it maybe suihcient tocreate adangerous condition.k `This is especially true lif theloadbeingprotected .byltheu circuit breaker is a motor or other-'type otrotating equipment. l 'd instant invention'is directed toa novelconstruction whereby the* how' of leakage Icurrent through the arcchute' whenf thefcircuit `breaker is in 'theopen l position is cornpltely eliminated. VIlachie've this Jdesirableresult'by'pr vjdingapivoauy mounted from: arehefarjwhich-wnl be engaged by the movablecontactarm whe is'iiritlieengaged or closed position? ICC y,The movablefront are horn is biased toward the front of the arc chute but movementthereof is prevented by the movable contact arm when the circuit breakeris closed. During the initial opening operation of the circuit breaker,the movable arc horn of my invention is in V-relationship withthestationary arc horn-associatedwith' the stationary contact member sothat a desirable venturi effcjctupon the arc will exist during theinitial opening operation. During the continued opening movement of theVmovable contact arm, themovable front arc horn associated therewith willfollow the movable contact due to the biasing force exerted ion thehorn. Thus, even though the archas been moved up into they arcextinguish-V ingmeans,l thekk continued electrical engagement betweenthe front arc horn and the movable contact arm will pro-f vide a returnpath for the current prior` to `the complete Aextinctiontothearc.k Thus,after the archas been liftedk ,forcedljnto the' are chute, the are will`be conned thefretolandthere will be no arcing to reionize the gasesfWithinrthe area occupied by the cooperating contacts.

rl`hat.is,.since there is acontinuous `conducting path from the movablefront are horn to the movable contact arm,v

there will be no arc inthis area and he'nce, no undesirable reionizationofthe air in thisk areawill result.

[n.theprior ,art arrangement, abovev described,`a 'per-V manent return.path :was provided from .the arc. chute. toI the movable` arc horn isothat a return path might bepro-r vided during the period oftimefollowing the movement ofuthe .movablecon-tact armpastthe front Yare.h'ornltill thetimethe movable archorn reachesapointfprior to its-However, after the movable contact armv has reached a point in theopening stroke where-the arc,

open position.

has .beeny completely extinguished, the yreturn through 4the movablecontact arm is not required.

ain/ly novel-apparatus is so 'constructed that after the guished, ltheelectrical connection between the movable front arcing'horn andthe'movable contact` armis automatically interruptedl thereby removingthe-'return path which is no=longer needed. Thus when the movable con-1tact arm hasreached its full open position, i. e.,in the staticopenlposition, no return path willexist` from ther arc chute through themovable Contact arm. Hence,v theY disadvantages'above noted with regardto the prior art arrangcmentis' eliminated;v That is, even though Aamoist atmosphere or other similar condition may exist to render the areplates of the arc chute partially `conductive,; `no return path willexist from the arc horn to the movable Contact arm due to the automaticseparation of they movable contact arm from the movable front arc horn.

yltfwilll be noted vthat it is necessary for automatic interrupting'equipment to withstand an impulse test whereby "a'predeterrninedvoltage can be applied across the openl or disengaged cooperatingcontacts without having breakdown'therebetween and also the circuitbreaker, must withstand this impulse'test without having leakage currentbetween its cooperating contacts. That is, the circuit breaker-must beable to withstand a'prede'termined magnr tud'e" of voltage acros'sitsopened contacts 'Withoutjstriking an arc therebetween and Without havingleakage current flowing therebetween. However, in the event a moistatmosphere exists, it is possible that the circuitbreakerv i's'prvided'inthe' prior arty arrangements. l--- l permanent return lead tothefront of the arc chute which With the pivotally mounted movable frontarc horn of my invention, the return path from the movable contact armto the arc chute through the return lead is eliminated. Hence, thecircuit breaker will be able to withstand the impulse test withouthaving leakage current flow between the cooperating contacts since alarge arc gap will not only exist between the cooperating contacts butalso between the movable contact arm and the arc chute or movable frontarc horn.

Accordingly, with my novel apparatus, the problems and disadvantages ofthe prior art circuit breakers having a exible permanent return path andmovable contact arm are completely eliminated.

The novel operating mechanism of my invention not only overcomes all ofthe disadvantages and problems of the prior art arrangements but alsomaintains all of the desirable features thereof. Thus, the operatingmechanism can he either manually or automatically closed and is providedwith trip free operation.

Accordingly, a primary object of my invention is to provide a circuitbreaker construction in which continuous contact engagement ismaintained between the movable contact arm and a movable front arc hornduring the initial part of the opening motion to thereby render itunnecessary to provide a return lead from the arc chute to the movablecontact arm in the nal open position.

Another object of my invention is to provide a pivotally mounted movablecontact arc horn for a circuit breaker which moves with the movablecontact arm and maintains electrical contact therewith during theinitial opening operation and thereafter permits the movable contact armto separate therefrom.

Another object of my invention is to provide an interrupting devicewhich eliminates the necessity fora permanent return lead from the arcchute to the movable contact arm.

A still further object of my invention is to provide an arcing horn andmovable contact arm combination which serves as a return connection tothe lower lead and the circuit breaker during the initial portion of theopening operation and also provides an air gap therebetween when thecircuit breaker is in the final open position.

Still another object of my invention is to prnvide a circuit breakerarrangement in which a V-relationship eX- ists between the arcing hornsin which one of the varcing horns serves as a return lead to the movablecontact arm.

A still further object of my invention is to provide a spring biasedmember which serves as an arcing horn and a return lead during theinitial opening operation.

Another object of my invention is to provide an arcing horn-return leadfor a circuit breaker which is in electrical contact with the movablecontact arm during the initial opening operation thereof with means tocause separation therebetween when the circuit breaker is in a finalopen position.

These and other objects of my invention will be apparent from thefollowing description when taken in connection with the drawings inwhich:

The figure is a side schematic view of one pole of a multi-pole circuitbreaker illustrating the position of the components when the circuitbreaker is in the closed position. The circuit breaker is provided withan upper line terminal 11 and a lower line terminal 12 which is bridgedby the movable contact arm 13. Movable contact arm 13 is pivotallymounted on one end of the line terminal 12 lat point 14, and at theother end contains the movable main contact 15 and the movable arcingcontact 16.

The movable arcing contact 16 may be pivotally mounted on the movablecontact arm 13 at point 17. The upper line terminal or side 11 isprovided with `a stationary main contact 18 and a stationary arcingcontact 19 which respectively cooperate with the movable main contact 15and the arcing contact 16. Arc chute 19 having a plurality of spacedparallel plates perpendicular to the arc ft formed between thecooperating contacts 15-18 and 16- 19 is positioned above thecooperating contact structure. The arc chute has a stationary back archorn 20 which is electrically connected to the upper line terminal 11.

The movable front arcing horn 21 which forms the basis of my inventionis pivotally mounted at point 22 and is biased in a clockwise directionby means of the spring 23 which is secured at one end to the arc horn 21and at its opposite end to some stationary point within the breaker. Themovable front arcing horn 21 is in continuous electrical contact withthe eXible metallic member 24 which is a continuation of a metal sidewall 25 of the arc chute 19. A stop pin 26 is permanently mounted Withinthe breaker to limit the counterclockwise rotation of the movable frontarcing horn 21, as will hereinafter be more fully described.

When the circuit breaker is in the closed position as indicated by thesolid lines of the figure, a complete current path will be provided fromthe lower terminal 12 through the pivot point 14 to the movable contactarm 13, main movable contact 15 to the main stationary contact 18 to theupper line terminal or stud 11. When the circuit breaker is in thisclosed position, the movable front arcing horn 21 is in electricalengagement with the movable contact arm 13 as illustrated.

When the circuit breaker starts to open, the main current path willtransfer from the main contacts 15-18 to the arcing contact 16-19. Itwill be noted that during this period of time, the movable front archorn 21 will be in continuous electrical engagement with the movablecontact arm 13. Following the separation of the cooperatlng arcingcontact 16-19, the arc will be transferred from the arcing contact 16-19to the stationary back arcing horn 20 and the movable front arcing horn21.

Since the movable front arcing horn 21 is biased in a counterclockwisedirection by means of the spring 23, it will be continuously urged intoelectrical engagement with the movable contact arm 13 during thisinitial opening operation. Thus, it will be noted that theV-relationship between the stationary back arcing horn 20 and themovable front arcing horn 21 will be maintained and thus, the arcextinguished therebetween will be under the influence of a venturieffect.

As the arc is moved up into the arc chute either by a blow out coil orthe above mentioned venturi effect and prior to the final open positionof the breaker, the movable front arcing horn 21 will continue to remainin electrical engagement with the movable contact arm 13 to therebyprovide a return lead to the lower terminal or stud 12. That is, as themovable contact arm 13 is continuously rotated in the clockwisedirection, the biasing spring 21 will continuously rotate the movablecontact arm 21 in a counterclockwise direction thereby maintaining anelectrical return path as long as the arc exists.

When the movable contact arm 13 reaches a point intermediate thecompletely closed position indicated by the solid lines and the fullyopen position indicated by the dotted lines, the movable arcing horn 21will be moved against its stop pin 26 to thereby limit itscounterclockwise rotation. Thus, following this initial movement of themovable contact arm, and after the arc has been extinguished in the arcchute 19, the movable contact arm 13 will continue to move to its fullyopen position and will no longer be in electrical engagement with themovable front arcing horn 21. That is, since electrical contact ismaintained between the arc horn 21 and the movable contact arm 13 duringthe initial movement of the arm 13 due to the biasing spring 23, therewill be automatic separation between these two members when the arc horn21 engages stop pin 26 and the movable contact arm 13 continues to moveto its fully open position. Thus, at the period of time after the arehas been extinguished and there is no longer a necessity for a returnline to the lower terminal 12, there will be an automatic separationbetween the arc horn'Zll` andi tact arm 13. p T ,p

Thus, I vhave provided ay novel. arrangement wh` n the member 21 servesas an arcing horn`immediatelyffn lowing `(second position) theseparation of the cooperating contacts and thereafter serves as a returnlea-d to the lower line terminal 12 when the movable contact arm 13 isin intermediate opening position;` '4 v i With the circuit breaker of myinvention,K the necessity of .a separatek independent return lead tothelower'line terminal 12 is completely eliminated by providing a novelmovable front arcinghorn. p u l A A Since an airgapexists betweent'he'movable front''avrcing horn and the movable contact arm 13 when thecircuit breaker is in the fully open position, there will be no dangerof leakage current owing through the arc chute when the circuit breaker10 is either on an energized line or subjected to an impulse test.

It will be noted that during the closing operation ot' the circuitbreaker, the reverse sequence of events will take place. That is, themovement of the movable contact arm from its fourth or fully openposition to a third intermediate position will bring the free end of thecontact arm 13 into engagement with the movable front arcing horn 21.Thereafter, as the movable contact arm 13 is moved from this thirdintermediate position toward its first or fully closed position,indicated by the solid lines in the drawing, it will push the movablefront arcing horn 21 in a clockwise direction about its pivot 22 againstthe bias of the spring 23. Thus, if the circuit breaker is in the fullyclosed position, the components will assume the position indicated bythe solid lines of the figure.

In the foregoing, I have described my invention only in connection withpreferred embodiments thereof. Many variations and modifications of theprinciples of my invention within the scope of the description hereinare obvious. Accordingly, I prefer to be bound not by the specificdisclosure herein but only by the appending claims.

I claim:

1. In a circuit breaker having a stationary contact and a movablecontact; said stationary Contact being electrically connected to oneline terminal of said circuit breaker and said movable contact beingelectrically connected to a second line terminal of said circuitbreaker; said movable contact having a closed and open position withrespect to said stationary contact; a stationary arcing horn and amovable arcing horn; said stationary arcing horn electrically associatedwith said stationary contact;

said movable arcing horn electrically associated With said movablecontact when said movable contact is in said closed position; a firstmeans to maintain said movable arcing horn in electrical contact withsaid movable contact during a portion of its travel from said closedposition to said open position; a second means to prevent electricalengagement between said movable arcing horn and sai-d movable contactwhen said movable contact is in said open position.

2. In a circuit breaker having a movable and stationary contact; saidmovable contact having an engaged and disengaged position with respectto said stationary contact; a stationary back arcing horn; saidstationary arcing horn permanently connected to said stationary contact;a movable arcing horn selectively connected to said movable contact; afirst means to maintain said movable arcing horn in electrical contactwith said movable contact during a portion of its travel from saidengaged position to said disengaged position; a second means to preventelectrical engagement between said movable arcing horn and said movablecontact when said movable contact is in said disengaged position.

3. In a circuit breaker having a movable and stationary contact; saidmovable contact having an engaged and disengaged position with respectto said stationary contact; a stationary back arcing horn; saidstationary arcing horn .A sition; aj first means to maintain saidmovable arcinghorn inl yelectric contact with said movable contactduring' a portionfof its travel from said engaged position to saiddissaid movable arcing horn spaced .from nt'act when said movablecontact is in said horn pivotsall? mounted on saidlcircuit 'breaker andbiased toward said movable contact; said stationary arcing hornpermanently connected to said stationary contact; said movable arcinghorn selectively connected to said movable contact; a first means tomaintain said movable arcing horn in electrical contact with saidmovable contact during a portion of its travel from said engagedposition to said disengaged position; a second means to preventelectrical engagement between said movable arcing horn and said movablecontact when said movable contact is in said disengaged position.

5. In a circuit breaker having a stationary contact, a pivotally mountedmovable contact, a stationary arcing horn, and a movable arcing horn;said movable arcing horn pivotally mounted on said circuit breaker andbiased toward said movable contact; said movable contact having a closedand open position with respect to said stationary contact; a biasingmeans maintaining electrical engagement between said movable arcing hornand said movable contact when said movable contact is in said closedposition and as said contact moves toward said open position; means tointerrupt the electrical connection between said movable arcing horn andsaid movable contact when said movable contact is in said open position.

6. In a circuit breaker with a movable contact arm having a first andsecond position; a pivotally mounted spring biased member mounted onsaid circuit breaker for electrical engagement with said movable contactarm when said contact arm is in said first position; said pivotallymounted spring biased member serving as an arcing horn when sai-dmovable contact arm is moved from said first position toward said secondposition; means to disconnect said pivotally mounted biased member fromsaid movable contact when said movable contact is in said secondposition sai-d pivotally mounted biased member serving as a return leadprior to said disconnection by said means, said means ineffective toprevent electrical contact between sai-d pivotally mounted arcing hornand said movable contact arm during a portion of the movement from saidfirst to said second position.

7. In a circuit breaker having an upper and lower line terminal;stationary contacts electrically connected to said upper line terminal;a movable contact arm pivotally mounted on and electrically connected tosaid lower line terminal; movable contacts mounted on the free end ofsaid movable contact arm; a stationary arcing horn and a movable arcinghorn; said stationary arcing horn electrically connected to said upperline terminal; said movable arcing horn pivotally mounted on saidcircuit breaker and biased toward said movable contact; said movablearcing horn biased into electrical engagement with said movable contactarm when said movable contacts of said movable contact arm are inengagement with said stationary contacts; said movable arcing hornremaining in electrical engagement with said movable contact arm whensaid movable contacts initially separate from said stationary contacts;said movable arcing horn in electrical engagement with said movablecontact arm to serve as a return connection when said movable contactarm is in a position between said initially separated position and fullyopened position; means to prevent the electrical engagement between saidmovable arcing horn and said movable contact arm when said movablecontact arm is in said fully opened position.

8. In a circuit breaker having a movable contact, a stationary contactand an arc chute; said arc chute positioned above said movable andstationary contact and hav,- ing a stationary back arcing horn and amovable front arcing horn pivotally mounted thereon; said stationaryback arcing horn electrically connected to said stationary con tacts;said movable contacts being in electrical engagement with said pivotallymounted movable rst arcing horn when said movable contacts are inengagement with said stationary contacts and also when said contacts areinitially separated; biasing means to maintain said movable front arcinghorn in electrical engagement with said movable 8 contacts when saidmovable contacts are in a position preceding the fully open position;means to render said biasing means ineffective to maintain electricalcontact between said movable front arcing horn and said movable contactwhen said movable contact is in said fully open position.

References Cited in the tile of this patent UNITED STATES PATENTS2,597,257 Nye May 20, 1952 FOREIGN PATENTS 168,849 Great Britain Aug. 4,1922

